Location of thermostat on 2003 chev s-10 4WD w/ V-6

I have not worked on that truck but thermostates are located where the upper radiator hose connects to the top front of the block. Remove that hose connection and then the 2 bolts holding the hose falnge, thermostat should be sitting right there, pull out with fingers or needle nose plyers.

Likely, it's under the housing where the top radiator hose attaches to the engine.

Here's a diagram:

Attachment 28026